But kids need to be able to figure out the right operation to use. And checking how well your class can problem solve gives you some indication of how deeply they understand the 4 operations. So we do a fair amount of problem solving in my class.
To make it a bit more fun (and to cut down on my photocopying), we usually 'Write the Room' when we practise solving word problems. I make up sets of 24 cards which are numbered. I laminate, cut the cards out, and post them around the room. Kids then arm themselves with clipboards, pencils and either jotters or a recording sheet, and set off to find and solve as many problems as they can. There is something about being able to be out of their seats, walking around the room, that seems to help them focus on the word problems, rather than the conversation they'd like to have with the person sitting next to them! It also gives my class a chance to choose a partner to work with, if that's what they'd like to do.
At the beginning of the year, we started off by solving problems with single operations (so all addition, then all subtraction, etc). This was good for getting them used to the procedure, but I'm not really a fan of single operation problem solving. I find that the kids don't really read the problem. They just find the 2 numbers and perform whichever operation we are work currently working on.
So now that everyone knows what to do when we are 'Writing the Room', when I'm making up sets of cards, I mix up the operations. Because we've now done all 4 operations (and are currently working on division), our problem solving is either multiplication & division together, or all 4 operations mixed up.
If you click on the above picture, it will take you to a file with mixed problem solving using all 4 operations. This is an early set, and almost all of the sums are within 30 (I think one card asks them to multiply 8 by 4, so your answer is 32).
I generally only put 12 cards up at a time. When we do maths stations, kids have 20 minutes or so at each station, so 12 problems is about right (although they usually have to finish the 'Write the Room' problems before moving to the next station). I sometimes use the first 12 problems to practise problem solving with my small groups before sending them around the room to solve problems 13-24. Or at times, I send them around to solve problems 1-12, then I keep 13-24 in reserve to use the next day (if they need more practise). There are a couple of different recording sheets at the end of the file that you can use (when I use recording sheets, I photocopy them double sided). Or alternatively, you can just let the kids solve the problems in their normal maths jotters. That's what I tend to do, now that the kids have the hang of this particular task. I just emphasise that they MUST number the problems, so I know which problem they are solving when I come to mark them!
I hope you find these useful. If you aren't keen to have kids up and moving around the room, these cards would also make a useful set of Task Cards for maths stations. I've also used them as a whole class activity. When I do this, the kids all have individual white boards, and they write their solution down. On a signal from me, they all show me their answers. This works pretty well, and can be a good way to assess who is and isn't ready to practise problem solving on their own.